QMI AGENCY

Unwed parents who want to tie the knot should do it before their child turns three, a new U.S. study has found.

That period between birth and the third birthday is a "magic moment" and marriages last longer when they occur during that time, the study by Duke University researchers said.

The study found 64% of children born to unwed mothers see their moms get married, but nearly half of those marriages end in divorce.

"These marriages are fragile," study author Christina Gibson-Davis said in a release. "If you think that stable marriage is beneficial for kids, very few kids born out of wedlock are experiencing that."

The odds improve somewhat when mothers marry their child's biological father, the study found. After a decade, 38% of post-conception marriages involving biological parents had dissolved, while 54% of marriages to a stepfather ended.